Process of extracting metals from ores or slimes.



No. 652,849. Patented July 3, I900.

S. H. JOHNSON &. H. L. SULMAN. PROCESS OF EX-TRAGTING METALS FROM'ORES 0R SLIMES.

(Application filed Dec. 11, 1899.)

(No Model.) 3 Sheets8heet I.

ma NORRIS PETERS cc. PuoTo-umo wnsmncrzmv u. c.

N0L65Z 849. Patented July 3, I900.

S. H. JOHNSON & H. L. SULMAN. PBDGESS 0F EXTBACTING METALS FROM UBES 0R SLIMES.

(Application filed Dec. 11, 1899.)

(No' Model.) 3 Sheets8heet 2.

n1: upmus PETERS co, Puamumo, WASNINGTGN, n. c.

No. 652,849. Patented July 3, I900; s. H. ammsou & H. SULMAN. PROCESS OF EXTRAGTING METALS FROM ORES 0R SLlIflES.

(Application filed D'ec. 11, 1599. (No Model.) 3 Sheets-Sheet 3.

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UNIT D STATES 'PATENT OFFICE.

SAMUEL HENRY JOHNSON AND HENRY LIVINGSTONE SULMAN, LONDON,

ENGLAND, ASSIGNORS TO THE S. SAME PLACE.

H. JOHNSON (it COMPANY, LIMITED, OF

SPECIFICATION forming part of Letters Patent No. 652,849, dated July 3, 1900.

Application filed December 11,1899. Serial No. 740,003- (No specimens.)

T all whom it may concern:

Be it known that we, SAMUEL HENRY JOHN- SON, residing at Stratford, London, county of Essex, and HENRY LIVINGSTONE SULMAN, re-

siding at London, England, subjects of the Queen of England, have invented certain new and useful Improvements in or Relating to the Extraction of Metals from Ores or Slimes, 'o

which the following is aspecification This invention relates to the extraction of metals from ores or slimes, and has for its object the removal of gold and other metals from finely-divided minerals or from slimes by chemical treatment-"in the wet process. The invention has particular reference to processes employing filter-presses for leaching the finely-divided ores or slimes, and is applicable, for instance, to such a process as is described in the specification of British Letters Patent No. 19,389 of 1891.

Finely-divided precipitated ores-such, for example, as the settled slimes which precipitate from the battery-tailings -contain alarge amount of water, the proportion in some cases being about five parts, by volume, of dry solid to fifteen parts, by volume, of water. In treating such material with chemical solutions such, fen-instance, as a solution of cyanid of potassium-the water present obviouslytends to dilute. the solution used, and consequently a greater waste of the chemicals must occur in the extraction of the metal than wouldbe the casefif the water, were not present. By the employment of filter-presses a considerable proportion of the water in the material may befexpressed. It is found that by this preliminary filter-pressing twenty parts, by volume, of settled slime yield about eight parts," by volume, of filter-pressed cake and twfl-ve parts, by volume, of filtrate, thus leaving behind in the cake five parts, by volume, dry solid and three parts of water ilkn important feature of this invention is the. elimination of the water which remains in the. pressed material in such a manner as to avo'd the expense of driving off such water I) heat, thus permitting of the treatment of et' or battery crushed ores and ore products ith the same economy as can be effected with dry materials.

This is accomplished by dis- 7 placing the Water remaining in the cakes after the preliminary filter-pressing by means of a cyanid or other chemical solution of normal strength. If precautions are taken in the pressing so that the cakes produced are uniformly permeable, thewhole o f the remain Witlr'only a very slight admixture of the chemical solution used. ,Owing to the fact that the displaced water contains a small amount of the solvent solution it will in the case of gold slimes contain some gold, and it is desirable in order to recover this gold with out diluting the bulk of the main body of solvent liquor to employ a small set of zinc boxes, zinc cones, or other convenient apparatus, theoverfiow from which may be allowed to run to waste. The main volume of the work- .ing solvent liquor is treated in another precipitatingapparatus,as hereinafterdescribed. For the purpose of correctly gaging the volume of liquid displaced from the cakes a graduated tank is employed, and when the effluent displaced from the cakes in the filter-press is equal to the volume of water that those cakes originally contained, the amount of such volume being determined in any particular case by a preliminary assay, the process of dis placement is considered to be complete. By thus removing a volume of liquid equal to the volume of the water contained in the cakes after the preliminary compression it follows the volume of the main bulk of solvent liquor subsequently employed in extracting the metal from the pressed material. The cakes from which the moisture has been displaced by means of normal solvent liquor in the filterpressing operations above described are then mechanically broken up and agitated with a sufficient quantity of normal solvent solution to bring them into a sufficiently-liquid condition to admit of their being readily treated with the solvents; but the mixture should not be made so liquid that the solid matter in suspension would readily settle therefrom. The amount of liquid required would be from once pending upon the relative facilities of diifering. water maybedisplaced by our process that no practical alteration will take place in to twice the volume of the cake or more, de-

ent ores for remainingin suspension in the liq 10o uid, the object being that there shall be sufiicient mobility in the liquid to admit of speedy solution of the precious metals and at the same time that there shall not be any tendency for the solids to settle out of the liquid in the chambers of the filter-press during the period of charging or in the other operations, as such settlement would tend to produce cakes which would not be uniformly permeablea condition which should be carefully guarded against. The best state of dilution may be easily determined upon for any particular ore by any one of experience and skill in such matters.

To insure the rapid solution of the metals and also that the solids shall be suspended in the liquor, so as to form a homogeneous magma suitable for working properly in the filterpresses, an improved mixing apparatus is employed, which is hereinafter more fully described. It is to be understood, however, that'this particular form of mixing apparatus is not absolutely essential to the carrying out of our process. Gtner convenient apparatus may be employed. After the material has been thoroughly mixed with the additional quantity of normal solvent solution it is treated in leaching filter-presses, and a large proportion of the liquid which now contains the metal in solution issqueezed out and allowed to flow directly to the zinc boxes or other apparatus where the gold or other metal is precipitated. After leaving this apparatus the liquid is returned to the strong-liquor tank. Some of the metal-bearing solution will remain in the cakes in the filter-press, and this is now displaced by means of water, the volume dis placed being gaged, as in the first part of the process, so that dilution of the solvent liquid is avoided. The displaced liquid is treated in the precipitating apparatus and is then returned to the strong-liquor tank. The washing is continued for the purpose of finally removing all traces of gold in solution from the cakes, and these washings are collected and are passed through a separate precipitating apparatus, from which the liquid maybe allowed to run to waste.

It will be seen that the process according to this invention may be summarized by stating that after aprelimiuary treatment of the material in a filter-press the water remaining in the cakes is displaced bya normal solvent solution, the material being then further mixed with the solvent solution and again treated in a filter-press, by means of which the metal-bearingliquid is removed partly by expression and finally by displacing it with water, the Whole of these operations being conducted so that an approximately-constant volume of the solvent solution is maintained.

In the accompanying drawings,which illustrate diagrammatically one construction of apparatus for carrying out the improved process, Figure 1 is a plan, Fig. 2 is a side elevation, and Fig. 3 a central vertical section, of the mixing apparatus to a larger scale.

Like letters indicate like parts throughout the drawings.

A and A are settling-tanks through which the liquid containing the finely-divided ore may flow continuously, the slimes being deposited by gravitation. From the settlingtanks the slime passes by means of a pipe A to a forcing-receiver B, which is supplied with compressed air through a pipe 0 communicating wit-h compressed-air reservoirs O and C these reservoirs being supplied from an air-compressor C. Preferably the forcingreceiver is arranged so that when the pressure of air is removed the receiver automatically refills the semiliquid slimes by gravitation from the settling-tanks A and A.

D and D are filter-presses used for the elimination of the water from the slime, which is supplied to them through the pipe D being forced up through the pipes 13 and D by compressed air.

The greater part of the water 'in the slime is expressed in the filter-presses D and D and passes through a pipe D to a tank E and thence to waste by a pipe E. The residual water in the cakes is then displaced or pushed out by means of solvent solution of normal Strength, which is pumped from a liquor-tank F through a pipe F by a pump G. The delivery-pump G of the pump G communicates with the bottom of the com-.

pressed-air reservoir'Q, and another pipe G2 leads from the same portion of that reservoir to the filter-presses D and D.

The tank E is preferably gagcd so that a calculated quantity of water may be displaced by the solvent solution, and when this operation has been performed, as he isplaced water may contain a small quantity of the solvent, it is passed through a pipe E to a small set of zinc boxes H or other convenient precipitating devices. After leaving the zinc boxes the liquid may be allowed to run to waste. Beneath the filter-pressesD and D is a chute J, into which the compressed cakes fall and are conveyed to a mixing apparatus K, hereinafter more fully described- The material while in the mixer K has ;an additional quantity of normal solvent {solution added to it, this solution being pumped bya pump K through pipes'K from the liquortank F. It is found that aconvenient quantity of the solvent is an amount {Vhich is approximately equal to the volume of ate mechanically expressed from the slime in the filter-presses D and D. After being-thoroughly mixed with the solvent in the apparatus K the material passes through a pipe li' to a second forcing-receiver L. This forcin receiver L is supplied with compressed air from the reservoirs O C through a pipe 0", and the material is forced up through the pipes L and L to a second set of filter-preses M andM. In these presses M and Mglio material is first compressed to extract t c more easily removable solvent solution, (no\ the metal-bearingliquid,)and then the rem ainin g portion of the liquid is displaced by means of water, which is forced into the presses M M through a pipe M by means of compressed air from the reservoir 0 The water is supplied to the reservoir 0 by means of a pump N, the delivery-pipe N of which communicates with the bottom of the reservoir. The expressed metal-bearing liquid is passed to a separate set of zinc boxes H or other convenient precipitating devices through a pipe M from whence it passes by a pipe H to the liquor-tank F. The displaced metal-bearing liquid passes through a pipe M to a graduated tank 0 and thence through a pipe 0' to the precipitating devices H. After the calculated volume of solvent has been displaced by the water under pressure more water is forced through the cakes in the presses M M in order to remove the last traces of metalbearing liquid. This liquid also passes into the tank 0, but owing to its weak condition is not allowed to pass to the precipitating devices H, but is passed through a pipe 0 to the small zinc boxes H, from whence the liquid maybe allowed to run to waste.

It will be noticed that the air-reservoirs G V and (J communicate by a pipe 0 and thus the air-pressure upon. the solvent solution and the washing-water is equalized.

Fig. 3 illustrates in vertical section an improved form of mixing device which is found to be extremely efficient. The general principle upon which this device works is similar to that described in the specification of Brit= ish Letters Patent No. 5,37 7 of 1892, and the present mixer constitutes an improvement upon the machines therein mentioned. The improved mixing apparatus comprises a vessel K, having a neck K and provided witha vertical shaft K suitably journaled at the bottom of the vessel. This shaft K carries a vane K which is formed with two disks K having between them ribs K which are curved or partly radial and partly curved,-

so that they act upon the liquid in the tank in a way similar to the act-ion of a centrifugal pump. The shaft K is driven by a small engine K, which is mounted upon the neck of the vessel K. Surrounding the shaft K ,within the vessel K, is a trunk-pipe K", which does not rotate, and at the top of this conducting or trunk pipe K a hopper K is provided, the mouth of which is only slightly smaller than the contracted neck K of the vessel K. The top of the tank is so shaped that it tends to cause the flow of liquid delivered from the centrifugal vane K to converge toward and overflow the rim of the hopper K in the form of a cascade. The object of causing the liquid to enter the hopper in this cascade is to secure the efficient oxidation of the liquid, when such is desirable, by atmospheric aeration. This eifect is further increased by providing the top of the hopper K with a rim or bandK ,which is perforated or provided with slots, such slots being preferably made without removing the metalmerely slitting it, so

as toform small flaps. Through these perforations or slots the liquid under agitation is delivered in cascade form into the hopper K In order to enable the mixing apparatus to work efficiently, even when it is not quite full, the circulating or trunk pipe K is arranged so that it is capable of sliding up for a short distance upon the shaft K This allows the liquid to fiow into the vane K between the trunk-pipe K and the top of the'vane, thus securing a thorough circulation and agitation at the bottom of the vessel K. The movement of the trunk-pipe K is effected by means of a cord or equivalent K, which passes over two pulleys K and is fixed to a support or spider K at the top portion of the trunk-pipe K. The other end of the cord K is fastened to a screw K which can be screwed in or out of its support K by means of a hand-wheel K.

The function of the trunk-pipe-K is to cause the liquid to circulate in a vertical direction, and the pipe K merely forms a feed-conduit to the centrifugal vane K at the bottom of the tank. It will be readily seen that with such a vane in the lower part of the vessel no deposition of fine sands can take place during the mixing operations.

When bromid of cyanogen is used or in other cases where oxidation is undesirable, the hopper K and the cascading arrange ment K may be omitted.

In the apparatus various cocks or valves are placed to control the respective pipes; but these form no part of the present invention and are omitted from the drawings for the sake of clearness.

As hereinbefore stated, it is to be distinctly understood that the apparatus described although forminga convenient means for carrying out this invention is not essential thereto, but may be varied in many ways while still carrying out the improved process.

What we claim as our invention, and desire to secure by Letters Patent, is-

1. The method of treating pressed slime cakes containing residual water, which consists in displacing the residual water in the cakes with a solvent solution.

2. The method of treating ores or slimes, which consists in removing a portion ofthe water from the ores or slimes by pressure, and then displacing the residual water in the pressed ores or slimes with an equal volume of a solvent solution.

3. The method of treating pressed slime cakes containing residual water, which consists in displacing the residual water with a solvent solution, mixing the cakes with a fur ther quantity of solvent solution, and remov ing the metal-bearing solvent solution by pressure.

4. The method of treating pressed slime cakes containing residual water, which consists in displacing the residual water with a solvent solution, mixing the cakes with a further quantity of. solvent solution, removing said metal-bearing solution, whereby all the operations may be performed with an approximately-constant volume of the solvent solution.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

SAMUEL HENRY JOHNSON. HENRY LIVINGSIONE SULMAN. Witnesses:

W. M. HARRIS, FRED. (J. IIARRES. 

